1. Field of the Invention
The present invention relates to a lens barrel in which lenses can be driven by an annular oscillatory wave motor disposed coaxially with an optical axis and in which lenses can be operated manually with a manual ring.
2. Description of the Related Art
Japanese Patent Laid-Open No. 02-253214 discloses a lens barrel in which lenses can be driven by an oscillatory wave motor with a ring having rollers rotatable about axes disposed at radial positions thereof (hereinafter, referred to as a roller support ring) and in which lenses can be operated manually with a manual operation ring.
With the structure disclosed in Japanese Patent Laid-Open No. 02-253214, when a user tries to continue to manually operate the manual operation ring after the roller support ring is brought into contact with an operating end, a portion with the smallest frictional resistance slips against frictional force. Usually, the portion slips at a place between the manual operation ring and the rollers, between the rollers and the oscillatory wave motor or, though in rare cases, between a rotor and a stator in the oscillatory wave motor. The roller support ring often has a complicated shape and is thus formed by resin molding. When a slippage of the rollers which are supported by shafts that are made of resin and are thus easily elastically deformable occurs, deformation of the shaft and friction may be caused alternately and repeatedly. This phenomenon may cause undesirable vibration and unusual noise.
The present invention reduces slippages between a roller and a member in contact with the roller when an operator tries to continue a manual operation after a roller support ring is brought into contact with an operating end.